Treating lead matte.



U. WEDGE.

TREATING LEAD MATTE.

APPLICATION FILED JAN. 29, 1913.

1,198,882. Patented Sept. 19, 1916.

F- i 2 SHEETS-SHIT l.

:NVENfo U. WEDGE.

TREATING LEAD MATTE.

APPLICATION FILED JAN. 29. 1913.

1,198,882. Patented Sept. 19, 1916.

2 SHEETS-SHEET 2.

vI/nNEssEs v INVENIQR W J W LJI Ey \A/ED E By Is IIO NE UNITED s'rA'rEs PATENT oEEIoE.

UTLEY WEDGE, 0F ARDMORE, PENNSYLVANIA.

TREATING LEAD MATTE.

To'rzll whom it may concern v Be it known that I, UTLEY WEDGE, a citizen of the United States, residing in Ardmore, Pennsylvania, have invented certain Improvements in Treating Lead Mattes, of which the following is a specification.

My invention relates to the roasting of lead sulfid, lead ores, lead'concentrates, lead matte, or other lead compounds (hereinafter referred to as lead matte) in furnaces of the superposed hearth'type, the object of my invention being to provide for the driving off of the sulfur without causing the fusing or sintering of the matte or rendering it sticky so as to interfere with the mechanical operation of the furnace.

Prior to my invention many attempts have been made to roast lead matte in furnaces of the superposed hearth type having mechanical rabbles, such for instance as shown in United States Patents Numbers 556,750, dated March 24,1896; 629,023,dated July 18, 1899; 648,183, dated April 24, 1900; 673,174, dated April 30, 1901; 700,339, dated May 20, 1902, and others. Such attempts have not met with success, because, in a furnace of the superposed hearth type, in

which the air for oxidizing the calcine is admitted at the lower portion of the furnace and the draft is upward to an outlet or outlets located in the uppermost treating chamber, the gases accumulate heat as they pass in succession overthe superposed hearths, the consequence being that, in the upper chambers of the furnace, so high a temperature is reached that the incoming supply of lead matte soon becomes sticky so that it cannot be stirred or moved over the hearth by the rabbles.

It has hitherto been possible to roast lead matte in single hearth furnaces because, in a single hearth furnace, there is no progressive concentration of heat such as occurs in a multiple hearth furnace, but on account of the high fuel cost of roasting lead matte in a single hearth furnace, either rabbled by handor mechanically operated, it has been desirable for many years past to accomplish the roasting of lead matte in a multiple hearth furnace.

In order to meet the 'difliculty encountered in roasting lead matte in a furnace of the superposed hearth type I made extensive investigations and found that lead matte containing a considerable percentage of sulfur (as, for example, twenty per-cent.) became Specification of Letters Patent.

Patented Sept. 19, 1916.

, Application filed ianuary 29, 1918. Serial No. 744,894.

1400 F., (a temperature much less'than that of the upper portion of a superposed hearth furnace operated in the ordinary way) but that, as the roasting progressed and the sulfur content of the calcine became less, the temperature to which the lead matte could be subjected without becoming sticky rose steadily, until, with a sulfur content of thirteen per-cent., the calcine could be subjected to a temperature several hundred degrees in excess of 1400 F., without encountering the difiiculty.

In carryingout my invention, therefore, I maintain a lower temperature in the upper portion of the furnace than in the lower portion of the same, preferably by abstracting heat from the gases rising from the lower into the upper chambers of the furnace, my purpose being to pass the lead matte downwardly from chamber to chamber of the furnace in the ordinary way and to maintain in the difierent chambers of the furnace temperatures sufficient to effect the desired sulfur elimination but not high enough to efi'ect sintering or cause the lead matte to become sticky. I The control of the temperature in the upper portion of the furnace, for example, in the first four chambers at the top of a seven hearth furnace, may be effected by different means, as for example, by hearths equipped I .No. 946,178, dated January 11, 1910, whereby the temperature of a chamber may be lowered or raised at will by increasing or decreasing the supply of air to the ducts, or rabble arms can be provided of such dimensions as to permit of the absorption of surplus heat by cooling fluid circulated within the rabble arms, as in my No. 916,234, dated March 28, 1909 the abstraction of heat from the chamber being controlled by the greater or less supply of cooling fluid to the arms in that chamber, or the gases from the lower portion of the furnace can be passed through a cooler be.- fore being admitted to the chamber or chambers above, or, in a 'muflle furnace, heat can be applied to the hearths wherein heat is necessary to secure the required elimination of sulfur and the chambers in which the temperature might become too high may be opened to the atmosphere to a greater or less extent, but to secure the advantages and Letters Patent the econom of direct fire I prefer direct application heat in the lower portion. of the furnace where a high temperature is necessary to carry the elimination of sulfur from the calcine to the desired point, and then, instead of allowing all of the hot gases to pass through the chambers above in series, I prefer to permit of the escape from such chambers, of such portion of the heated gases as may be necessary to avoid excessive temperatures therein, such escape being effected preferably from several regulable outlets in each of such chambers so that the higher fuel economy may be attained by using all of the heat that can safely be used in the lower portion of the furnace, applying the same to the upper treating chambers of the furnace but abstracting such portion of the same as may be necessary to avoid reaching the sticky or sintering temperature in any chamber of the furnace.

In the accompanying drawings I have illustrated so much of a furnace of this type as is necessary for a proper understanding Fig. 2 a transverse section on the line a-a, Fig. I

This furnace has seven treating chambers numbered from top to bottom 1, 2, 3, 4, 5, 6

and 7, the chambers 1, 2, 3, and 4: being provided with dampered outlets 1, 2, 3 and 1? whereby the escape of the heated gases sulfur has been so far reduced as to permit.

of the free application of the heat necessary to effect the desired desulfurization, and then applying such higher heat.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

. UTLEY WEDGE. Witnesses:

KATE A. BEADLE,

HAMILTON D. TURNER. 

